An intarsia fabric is formed by performing a knitting operation with different knitting yarns without separating a knitted fabric while performing switching among several yarn feeders during a 1-course knitting operation.
In this intarsia knitting operation, a plurality of yarn feeders 12a and 12b are slidably disposed in a yarn guide rail as shown in FIG. 12. Yarns are fed to knit a first knitting area A by means of the yarn feeder 12a and to knit a second knitting area B by means of the yarn feeder 12b, and switching is performed from the yarn feeder 12a to the yarn feeder 12b at a switching point where a yarn is changed to another. When the yarn feeder 12a finishes feeding a yarn to the leftmost needle among needles used to knit the knitting area A from the right, the yarn feeder 12a has already been positioned left beyond a fabric boundary position P1 (i.e., a state shown by the alternate long and two short dashed line in the figure).
The reason why the yarn feeder moves beyond the boundary position P1 in this way is to allow the yarn feeder to travel ahead of the needle forming a loop so as to lower the position of a knitting yarn that extends from the yarn feeder to the knitted fabric and so as to reliably catch the yarn in a hook of the needle.
If the yarn feeder 12a is left at that position, the trouble arises in which a knitting yarn T that extends from the yarn feeder 12a diagonally right-downward is fed to a knitting needle that knits the subsequent second knitting area B by mistake.
Therefore, in order to eliminate this trouble, a yarn is fed from a feeding mouth of a yarn feeder selected by a leading means, a yarn feeder that is knitting, for example, the knitting area A is then released from being led at a boundary position of a knitted fabric, and the yarn feeder is stopped by a braking device.
When the leading means is further slid while the yarn feeder is being stopped by the braking device, the feeding mouth of the yarn feeder is moved from the yarn feeding position to a standby position placed inside the knitting area where knitting has been performed so far. According to this method, it becomes possible to prevent trouble in which a yarn is incorrectly fed to a needle used for the adjoining knitting area (see Japanese Patent Publication No. Sho-61-51061, for example).
The position of a yarn is lowered proportionately as the yarn feeder greatly moves beyond the boundary with the adjoining knitting area, and, as a result, a yarn feeding condition can be improved. However, since the feeding mouth is released from the leading means at a position exceeding the boundary with the adjoining knitting area, the amount of swing of the yarn feeder 12a must be increased correspondingly to the amount necessitated to retract a yarn extending between the yarn feeder 12a that has stopped inside the adjoining area A and the knitted fabric to a position that does not obstruct the operation of knitting the area B.
If the amount of swing of the yarn feeder 12a is increased, a swinging mechanism of the yarn feeder is enlarged and complicated.
When the yarn feeder is changed from the yarn feeding position to the standby position placed inside the knitting area, the amount of swing of the yarn feeder needed for a change from the yarn feeding position to the standby position is increased in a gauge in which a fabric is rough or in a needle-jumping-over knitting operation in which a knitting operation is performed by disposing a blank needle for transfer between needles used to form a loop as disclosed in Japanese Patent Application No. Hei-11-111717. Therefore, there is a fear that a knitting yarn will snap if the yarn is fragile.
On the other hand, when a yarn is changed to another, fabrics must be joined together according to a so-called “tuck joint” at the fabric boundary in which a tucking operation is performed with a needle used in the adjoining knitting area, and a subsequent knitting course is formed before switching is performed between yarn feeders so that a newly selected yarn feeder starts feeding a yarn.
The “tuck joint” will be described with reference to FIG. 3.
FIG. 3 shows a tuck joint at the boundary between the knitting area A and the knitting area B of FIG. 12 in which an alternate long and short dashed line represents the boundary therebetween.
A needle 5a is the leftmost one in the knitting area A, and a needle 5b is the rightmost one in the knitting area B. A yarn feeder is moved from the left to the right in FIG. 3. After a loop is formed with the rightmost needle 5b in the knitting area B, leading is released, and the yarn feeder is swung to a standby position shown by the alternate long and short dashed line.
Thereafter, the knitting area A is knitted by another yarn feeder, not shown, from the left to the right, is then knitted from right to left in a subsequent course, and the yarn feeder is swung to the standby position in the same way as a yarn feeder used to knit the area B.
Thereafter, a tuck joint is performed in the knitting area A by means of the yarn feeder used for the knitting area B when the knitting area B is knitted from right to left.
FIG. 3 shows a needle-jumping-over knitting operation in which a loop is formed with every second needle. Therefore, the tuck joint of the knitting area B is performed with a knitting needle 5c, jumping over the needle 5a adjoining to the fabric boundary.
In a course in which the area B is knitted from right to left, the yarn feeder is swung from the standby position to an upright position shown by a solid line. After that, the needle 5c used for a tucking operation is raised, the yarn feeder is then moved from right to left, and a knitting yarn slid toward the backface of the needle is fed toward the surface of the needle 5c. 
There has been a fear that the yarn will not turn to the backface of the needle 5c so that the needle 5c fails to catch the yarn when the needle 5c used for a tucking operation is raised in the vicinity of the yarn feeder.
Thus, if the needle 5c for a tucking operation is placed far from the fabric boundary, the yarn feeder must be greatly swung, and, disadvantageously, the yarn feeder is enlarged.
A description has been made of a case in which a needle-jumping-over knitting operation is performed as shown in FIG. 3. However, even in a with-all-needle knitting operation in which a knitting operation is performed without disposing the blank needle between the needles used to form a loop, the same problem as in the needle-jumping-over knitting operation arises because a tucking operation is performed with a needle situated outside the needle 5c, for example, if a knitting width of the area B is increased rightward to the extent corresponding to one needle so that the needle 5a can be used for the area B.
Additionally, since a flat knitting machine of a rough gauge has a large interval between needles, the aforementioned problem may occur even if the needle-jumping-over knitting operation or the width-increasing knitting operation is not performed.
The present invention has been proposed in consideration of the aforementioned problems. It is therefore an object of the present invention to provide a yarn feeding device of a flat knitting machine capable of obtaining the same effect as in a case in which the amount of swing of a yarn feeder is substantially increased without increasing the amount thereof and to provide a yarn feeding method thereof.